[NTG-context] Flow Charts

I find the chart module great, it provides good results when typesetting flow charts in many cases. However, sometimes when defining connection lines the automatic routing feature is not able to find an optimal route and lines intersect. I was wondering if there is an alternate way to define a particular path for a specific connection. Instead of letting the module doing that connection I would rather let it undefined and use some metapost commands to do it. Is there an easy way to do it keeping the lines and arrows setup?. Thanks!